Solvent extraction



1953 A. w. FRANCIS ET AL 2,563,670

SOLVENT EXTRACTION Filed Dec. 4, 1951 1. 4 Sheets-Sheet l AROMA no use Asr/u. 9 i A. EXTRACT /2 8 3L RECYOLE, 2 l HYDROCAR80N COLUMN 4 i ITR/ETHYLENE MAKE-UP 61mm TR/ETHYLENE Q 1 GLYOOL I-IYDROCARBON j FEED! vQ N I ,4 7 NONAROMAT/ STILL F57 R0 MAKEUP "5x31702214 T/g FLUOROOARBON-a FLUOROGARBON F/G. I INVENTORS ALFRED W. FRANCIS GEORGE 6. JOHNSONAGENT Dec. 22, 1953 Filed Dec. 4, 1951 FIG. II? A BENZE/VE TR/ETHYLENETI-HEPTANE' GL YGOL FIG. .1?

BENZENE ETHYLENE Z7-HP7ZNE D/FORMATE FIG. E2

BENZE/VE TR/ETHYLENE CYCLO- GLYGOL HEXA/VE A. w. FRANCIS ET AL SOLVENTEXTRACTION 4 Sheets-Sheet 4 PERFLUORO' METHYLDECAL/N F /G. E

BENZ/NE vT'I'HEPT'ANE ACETON/TR/LE DHEPTA/VE Ham BE/VZENE ETHYLEIVECYCLO- DIFORMATE HEXANE TN V EN T ORS ALFRED w. FRA lVG/S BY GEORGE C.JOHNSON AGENT 'of aromati s Patented Dec. 22, 1953 bury, N. J.,'as'sig'nors to socon'y-vacuilm Oil Company, Incorporated, a corporationof new Application December 4, 1951 Serial No. 259346 12 Claims. (01.196-14.2)

This invention has to do with extraction with certainselective'so'lvents of various mixtures, and particularly of hydrocarbonmixtures, to separate this mixturesinto fractions having "differentprop- -er res.

I. FIELD OF'I'NVENTION Numerous processes have been developed for theseparation of hydrocarbons and hydrocarbon derivatives of differentmolecular configuration by taking advantage of their selectivesolubility in-selected reagents orsolVent-s from which they later can beseparated, Exemplary of hydrocarbon separation procedures is theEdel'eanu procjess, wherein parafilnic "materials "are separated romaromatics by virtue of the "greater solubility in liquid sulfur-dioxide. Lubricating oil solvent refining processes, solventdeasiphalting, solvent dewaxinjg and the like are further examples ofthesepar'ation of hydrocarbons of different molecular configuration.

Many materials have been {proposed and some of them have been used asselective solvents for effecting separation of differentclasse's ofhydrocarbons. They vary greatly in selectivity and in applicability forvarious "boiling ranges of hydrocarbons. For the same boiling range thesolubility increases in the order, parafiins, naphthenes, olefins,'alkyl benzenes andppolycyclic aromatics for practically all availablesolvents. For many extractions this is a convenient order, since smallquantities-oi polycyclics which are detrimental 'to the viscosity indexof a lubricant, can be removed by suitable solvents. For example,aromatics in hydrocarbon mixtures have been concentrated by treatmentwith aniline, phenol, many derivatives of aniline and phenol,acetonitrile, benzyl alcohol, dip'ropionitriles, furfural, furfurylalcohol, methyl and ethyl sulfates, nitromethane, etc. At lowtemperatures, sulfur dioxide, chlorex, nitrobenzen'e, etc, have beenused. .Many of these, such as sulfur dioxide, are. unsuitable forconcentration of benzene except with wash oil, because they are misciblewith the hydrocarbons of. boiling point similar to that of benzene. Allof the aforementioned solvents dissolve aromatics in preference tonone-aromatic hydrocarbons.

In some cases, a reverse selectivity is more convenient andadvantageous. For example, such a selectivity-for non-aromatics inpreference to aromatics-is advantageous for removing a small quantity ofnon-aromatics from an essentially aromatic fraction.

Fluoroearbons, which have only recently been given attention n thechem'ica1 art, and of which relatively little is known -to date, havenow been found to have a, preferential selectivity in aromatics as.opposeitlfto aroma res.

This invention is predicated-upon the discoyery or advantageous andpractical Solvent "extraction procedures in which a fluorocarbon "used:al'o'ne 1) Incompletely miscible "with the 'nyiirbearbon mixture, y V V(2) Incompletely miscible with the fluorocarbon, (3) Forms three phaseswith the hydrocarbon mixture and the fluorocarbon and 4 "Has areferentia smmt far aromatic hybons. as pposed to nomaromatiehydrocarbons.

"It has also been discovered that a hydrocarbon fraction having a highconcentrates-11hraromatics can be further concentrated by contacting theSame With a fluorocarbon.

III. OB'JECTJS It is an object of this invention, therefore, to providean efiective means for sepa ating a multiplicity of fractions (or compouds) of 'di fie'iefit properties from mixtures containing the sam It isalso object "of this invention to provide for the Selective Slfiralfiibhof several hy ro arboil fractions "of different properties frothhydrocarbon mixtures. An im ortant object is the selective separation ofseveral hydrocarbon nactions, differing in properties, from ydrocarbonmixtures within themolecular weight range of about to about 400. Afurther object to selectively separate nomaroifiaties, parasite andoripaphthenesrrom mixtures containin the Same. Still another Object isto separate benzene and benzene hydrocarbons from mixtures eontainingfth'e sam one other object is to provide more highly aromaticconcentrates from hydrocarbon fractions havin'ga relatively High eoncemtratibn or "aromatics.

Other objects and advantages of the invention will be apparent from thefollowing description.

IV. INVENTION IN DETAIL As indicated above in section II, this inventionemploys a fluorocarbon (A) alone or in combination with a second solventwith which it cooperates. The fluorocarbons contemplated herein arethose which are liquid under extraction condi tions, which have at leastabout four carbon atoms per molecule, and which have substantially allfluorine atoms associated with said carbon atoms. Instead offluorocarbons, hydrocarbon derivatives in which at least about 80% ofthe hydrogen has been substituted by fluorine and fluorocarbonscontaining one or more other halogen atoms in the molecule can be used;typical of such compounds are CvI-IFrs, C7C1F15 and C'IHC1F14.

Preferred for the purposes of this invention, however, are thefluorocarbons represented by the general formula CzFy wherein :1:represents the number of carbon atoms and is an integer from about fourto about 20, and y represents an integer from about 8 to about 40. Thefiuorocarbons can be of straight chain or of cyclic configuration.Illustrative of such fluorocarbons are: perfluorobutane (041?10);perfluoropentane (CsFi-z); perfluorohexane (CsFu); perfluoroheptane(C'lFlG); perfluorodimethylcyclohexane (C3Fl6); perfluoromethyldecalin(C11F20). Methods of preparation of such compounds are now wellestablished in the art, and no detailed discussion thereof is believednecessary. By way of illustration, however, typical methods aredescribed in U. S. Letters Patent 2,462,345, 2,462,347, and 2,427,116;and a bibliography of fluorocarbons is given in Industrial andEngineering Chemistry, 39, 367 (1947).

Fluorocarbons found to be particularly advantageous herein areperfluorodimethylcyclohexane, perfluoromethyldecalin, andperfluorokerosene.

As indicated above, this invention employs with the aforementionedfluorocarbons (A) solvents (B) which are incompletely miscible with thefluorocarbons and with the mixture to be extracted, which form threephases with the fluorocarbons and mixture, and which have a preferentialaffinity for aromatic hydrocarbons. If the solvents are not normallyliquid, they also should become so in contact with the fluorocarbons orshould become so at somewhat higher temperatures in a temperature rangepracticable for extraction. Included among this class of solvents arethe following: acetic anhydride, acetonitrile, aldol, aniline,anisidines, benzoic anhydride, benzyl alcohol, carbitol, chloroaceticacid, p-chloro aniline, fi-chloroethanol (ethylene chlorohydrin)chloromaleic anhydride, p-chlorophenol, a-chloropropicnic acid, cinnamicaldehyde, cinnamyl alcohol, 2,4-dinitrochlorobenzene, diethylene glycol,dipropylene glycol, diethylene glycol monomethyl ether,5,,3'iminodipropionitrile, pfi'oxydipropionitrile,5,;8'thiodipropionitrile, ethylene diamine, ethylene diformate, ethylsulfate, ethyl tartrate, furfural, formanilide, furfuryl alcohol,c-hydroxyethylacetate, ,B-hydroxypropionitrile, lactic acid, maleicanhydride, methanol, ,B-methoxyethanol, methyl furoate, methylphthalate, methyl sulfate, monoacetin, o-nitroanisole, nitrobenzene,nitromethane, phenetidines, phenol, phenylethanolamine, phenylphthalate, piperonal, liquid sulfur dioxide, 'tetrahydrofurfurylalcohol, triethylene glycol and succinonitrile. All of these have beentested and found to be operative. To

be practicable, a solvent should have a limited miscibility with thenon-aromatic hydrocarbons. and should also have an appreciable solventpower for the aromatic hydrocarbons. This should be at least about twoper cent at a practicable operating temperature. Particularly preferredherein are triethylene glycol and diethylene glycol.

The foregoing solvents and the aforementioned fluorocarbons areeffective in resolving various mixtures into a multiplicity offractions, or compounds, of different properties. They are particularlyadvantageous in the resolution of aliphatic hydrocarbon-alkylbenzene m ix t u r e s, naphthene alkylbenzene mixtures, gasolines, fractions fromhydrogenated coal, etc.

With regard to hydrocarbon mixtures suitable for extraction herein, itis recommended that mixtures boiling below about 150 0., or having anaverage molecular weight of less than about 120, be used. Fluorocarbonsare less satisfactory as selective solvents for hydrocarbons ofmolecular Weight about 140-200, as illustrated by n-tetradecane,inasmuch as they are practically immiscible therewith. Observedsolubilities (weight per cent at 25 C.) in perfiuoromethyldecalin are0.45 per cent of n-tetradecane and 0.42 per cent of alpha-methylnaphthalene.

An advantage of using a fluorocarbon and a solvent of the characterdescribed above, is that the selectivities are additive. Thefluorocarbon solvent thus extracts a higher proportion of thenon-aromatic hydrocarbons than it would from the mixture alone, becausearomatics have been depleted from the mixture by the other solvent.Reciprocally, the other solvent produces a higher concentration ofaromatics, because non-aromatics have been depleted by the fluorocarbonsolvent. It follows, therefore, that in view of the oppositeselectivities of fluorocarbons and other solvents contemplated herein,any substantial miscibilities of the two solvents is intolerable forthis invention. Observed solubilities (at 25 -C.), to illustratedesirable solvent combinations, are: solubility of perfluoroheptane,C'IFIG, in triethylene glycol, 1.4 per cent; of perfluoromethyldecalin,CiiFzo, in triethylene glycol, 1.0 per cent; solubility of triethyleneglycol in fluorocarbons, less than 0.5 per cent. In general, solubilityrelationships of a fluorocarbon and a second solvent should be belowabout 5 per cent, and preferably below about 2 per cent.

In order that this invention may be more readily understood, typicalsetparation procedures are described below with reference being made toFigures I, II and III attached hereto.

A suitable procedure for treating charge stocks high in aromaticcontent, for example over by weight, is shown by Figure I. A charge suchas a mixture of parafiins and alkyl benzenes boiling in the range of '75to 115 0., and containing of aromatics, is charged through line I to acentral section of column 2. A fluorocarbon such asperfluoromethyldecalin is introduced into an upper section of column 2via line 3 A second solvent, advantageously triethylene glycol, is fedinto a lower section of column 2 through line 4.

The fluorocarbon is withdrawn at the bottom of tower 2 through line 5together with its non-aromatic (paraflin) extract. Thefluorocarbon-paraflin mixture is fractionated in still 6, with theparaffins being removed overhead through line i; any aromatics in still6 will be removed overhead with the parafiins. Fluorocarbon is removedli e 22 T th ene l co artifac s a omatics iro the ries nd i emo ed oge ew h it a ersatis ext act t r ugh ine i, extract s fraction-- ated in517111 9; omatics 93k?! l lhfifild through line l and triethylene glycolis removed from still 9 through line 4 and is recycled. Any es n til ae. remov d overhead- W the aromatics.

Generally, of the three layers formed in the o mn or xtractor 2., h fl ooca bon of density 1.7 to 2.0 will form the bottom layer. The secondsolvent, usually of dens ty 51-8. to- 1 will form the middle layer, andthe hydrocarbon feed of density 0.65 to 0.9 form the top layer. Ofcourse, ifthe hydrocarbon feed is highly aromatic (density a e 1 1335 5@2 1 2b? QQQ'fiQQ bon solvent is of low density, the layers will be inadifierent order. 7 a 7 Provision is madefor escape of hydrocarbons fromcolumn 2 by including escape line H at the top of column 2. Line II haspump l2 included therewith such that escaping hydrocarbons can berecycled to column 2 with feed.

Provision is made for replacing any solvents lost from the system;make-up fluorocarbon and make-up triethylene glycol are added throughlines I3 and M, respectively.

' Conditions of operation in column 2, of necessity, can be variedconsiderably, depending upon such factors as: concentration of aromaticsin the hydrocarbon charge; concentration of aromatics desired inaromatic extract; completeness of recovery of aromatics desired;particular fluorocarbon used; and particular second solvent used. Ingeneral, temperature and pressure of operation are limited only byeconomic considerations. The ratio of fluorocarbon to hydrocarbon chargeis preferably from 1:1 to :1, and the ratio of second solvent tohydrocarbon, for example, triethylene glycol, is preferably from 1:1 to20: 1.

Figure II illustrates a procedure similar to that illustrated by FigureI, but in the secondprocedure (II) acetonitrile is used in place oftriethylene glycol. Actonitrile has a low density, 0.735, With theresult that the undissolved hydrocarbon comprises the middle layer.There is no recycle or escaping hydrocarbon, and the aromatic extract isremoved from the top of the column. or extractor; Acetonitrile (B. P. 82C.) is not well a apted for extraction of benzene (B;- P. 80f- G.)

ecau e of the dif i ty ofssparat ns' the two omp n s b d s o S ecfically. a -hishly aromatic hydrocarbon feed,or exampleone cone emme toue i e 2 s ed nte aesnt section of e i m r 2? her n it is con racted wis u ro r o such as ner iue me n i ee slim, nd w h eseton lse The fimrecarton led into extractor 22 at an upper section via line 23, andacetonitrile is fed into a lower section vial line 24.

Fluorocarbon and parafiinsextracted from the feed, together with arelatively small quantity of aromatics, are removed from extractor 22through line 25 and are fractionated in still 26. The hydrocarbons,paraifins and some aromatics, are removed from still 26 via line 21. Thefluorocarbon is removed from still 25 via line 23 and is recycled toextractor 22.

eeeiqei r e end r m ti s, cemented therewi o ether with a mall quantityf no are t k om a to t rou h ine t totill Z AQet-Qe ls i taken over eadic-cash ine extractor: 21% preferabl ov s on i sisds tor adding ma ei111orocarbon an flefitonitrile to. the 'sys m by lines $2 and 3 esp ctel eEis s a c arg such s a mix e of rarafl nsa d el rlbenze ss boilin nthe. ran at 75: to 15. "At pical hares ontains .39 tesers mnt'br We ght.a om tics bu o her v icrmtmtion a e sn tch Sin e th sol ili r' a s finsin i is sa bonsis ow it i un con m c lip-Provide fluoro arbo to dis ivall at the new iles T u the proc dur sh ir r Figu e-Ill mc e. that most.i th c ncentra in accom li hed with the non-fluorocarbon solvent,tristhr sne slimlithe us d to scru o matte-s mt e hylene-girlish hares1s t thrflush line 4 n olum r e t h neslyesl 11 G.) in 43 1s inoduced-"into airp er 1 11 of col n 4 It i l e' nders ood t at t col mo43' di ecti nalso nte urr n sta e tow r xtrac i n e u men Con a of ti sand livdr carhons an a so e id ytes-veil a rae-matsri lin c lu nhetemnsra ure Q the mixt re: and: so en in 4% should b within he ran oabou 10 to x50 0-. heore su eelso sh ulde of he Qrd ro Q to 10thsra io fsolven ri th l ne lyc l tohydroca ben mi re n th maintaine w in the an eo :1 to: 2 21;. d endent hem -in. u o the conce tra ion o aromatics inhe char e mixure an the de iredoncsntrat on of the are mails: f act nsbe charme fe tu e is explained in more detail hereinafter with, refereencs'taa phase d gram; EieureIV-A. for the sy tom snzsnatriet rlsneelrce n-heptane Arafii ateis r moved Ii am col mn 42 hr ug lin 4 a id-isi troduced i o a st i N naromatics are tak n; overh ad fro sti 4 hrou h.l ne 45. and be us mov d tromthe syst m, Thence-ar matics. as herparaffin can be ur he concen rate if desired by u ther extract on 'l-rethr enc ly ol s emoved. from st l .5 hrou h line H nd i y d to. co umn525 via line 43 Th ex ac from ex act r omp se ematics, triethyleneglycol and a relatively small amount of paraflins- Th s xtr t s takthrou h lin B: to. whir 1:;v or extra 4 being introduced 11 a lowersection thereof. A fluorocarbon, such as perfiuoromethyldecalin, isintroduced into anupper section of column 49 through line; and comesinto contact therein 1 about 0 to 50 renovationof h arcma i trac s to beo tamed. is also explained in greater detail h re elow c nnection with aha diagram, Figure I l- 3 for heys m ze e-refi er ms hy isew m rhsntsns-The from c lumn 49 comprises. triethylene glycol and aromatics, with a.minor quantity, if any, of fluorocarbon. This raffinate is removed fromcolumn 49 through line to still 52. In the latter, aromatics are removedoverhead through line 53, and are so removed from the system.Triethylene glycol is removed from still '52 through line 54, and istaken to line 43 for recycle in column 42. Any small amount offluorocarbon in the triethylene glycol in still 52 can be recycled withit to the column 42.

The lower or extract layer in column 49 is removed through line 55 tostill 55, wherein removal of fluorocarbon is effected through line 40.Hydrocarbons, predominantly paraflins, in the fluorocarbon extract areremoved from still 56 through line 51 and recycled to column 42 asshown.

Make-up fluorocarbon and make-up triethylene glycol to replace any lostsolvent, are added to the system through lines 58 and 59, respectively.

The invention is further illustrated by experimental data obtained withfluorocarbons and other solvents recited hereinabove. These experimentaldata are presented in the form of charts, or more particularly ternarydiagrams, identified here as Figures IVA to VIII. These diagrams can beused to determine: the suitability of a solvent for the desiredseparation; the selectivity of the solvents; the range of composition offluorocarbon, other solvent, and the mixture to be treated; the numberof stages or extractions necessary to effect a separation of desireddegree; etc. The binodal curves were observed by making up syntheticmixtures until they just mixed or just separated. The tie lines showingcompositions of layers in equilibrium were ana-. lyzed by comparingtheir densities with those of known synthetic mixtures along the binodalcurves.

Figure IVA represents the system benzenetriethylene glycol-n-heptane,and Figure IV-B represents the systembenzene-perfluoromethyldecalin-n-heptane. Figures IVA and IV-B revealthat triethylene glycol is selective for benzene, but not for n-heptane,and that perfluoromethyldecalin is selective for n-heptane and not forbenzene. Thus, the selectivities of the two solvents are opposite, andas such are additive and cooperative. The respective hydrocarbons becomemore soluble in each solvent because of removal of less soluble materialby the other solvent.

Referring further to Figures IVA and IV-B, it should be noted that thebinary solubilities in weight per cent at 25 C. are as follows:

Solubility in triethylene glycol of-- The orientations of the tie linesin Figures IVA and IV-B are consistent with the binary solubilities.That is, the tie lines of Figure IVA, if prolonged, would intersect theleft side line so that the concentration of benzene in the hydrocarbonportion of the extract (left side of the binodal curve) is higher thanits concentration TABLE 1 Percentage of benzene in extractionTriet-hylene glycol Perfiuoromethyldccalin Extract Rafiinate ExtractRailinatc From the foregoing tabulation, it will be noted that there ismore selectivity exhibited by triethylene glycol, than is exhibited (inthe reverse direction) by the fluorocarbon. However, it will also beobserved that with higher concentrations of aromatics, there is greaterselectivity exhibited by the fluorocarbon. This is advantageous becauseone object is the removal of the last portion of non-aromatichydrocarbons from mixtures. This is also advantageous since it is mostdifficult to remove the last portion or" non-aromatics by contacting amixture with a single solvent such as triethylene glycol.

Figure V represents the system benzene-ethylene diformate-n-heptane, andreveals the selectivity of ethylene diformate for benzene. observedenrichments with ethylene diformate are shown below in Table II:

TABLE II Percentade of benzene in extraction Extract Raiiinate 1 Limit.

TABLE III Percentage of benzene in extraction Extract Rafiinate Limit.

Data has also been obtained with a fluorocarbon comprisingperfluorokerosene, corresponding to CnFzi and containing 77% fluorine.This fluorocarbon has a density of 1.90; Binary solubil-lties in weightper can at 25 c; with this fluorocarbon 1319' An abated enrichrnentobtained with perfluorokerosene is the following, Table IV:

ME .V. Percentage of benzene in extraction Extract Raflinate involvesseparation of All data given above,

a'ti

t was. lTABLE V Percentage of benzene in extraction 'Iriethylene glycolEthylene difor rnate Perfiuorokerosene in r r555; -i-.;w ExtractRaflinate Extract Raffinate Extract Limit.

Solubilities of perfiuoromethyldecalin and cyclohexane, and ofperfiuorokerose iand' cylo hexane.are-asfollowsf""""*" solubility Ieriluorornethyldecalinpf Cycl'ohexane 4 5 Solub11ity in perfiucyclohexane' 3.45 Solubility orperfiuorome'thyldecalin in Cyclohexane 9.1 Solubility effieinuerokerosene 1n cyclohexane"c;;;" ;';1 4.9

It will be obvious to thoseskilled in the art that some of theifiuorocarbonsc contemplated hrein are less desirable'than othersfoiseparatinlg 'a particular DQIA-aromatic hydrocarbon from "a m xt re-Correspondingly, some of the" "other solvents contemplated herein foruse with said fiuorocarbonsfaife'i'les's' iiesirable than others for erat pa l r swee hrdraqarbp rq i mt- W? I". fl such asperfiiioroh'ep'ane' (G-F16) has a g point of 82.43" C. and perfluorodimethylcyclohexanehas a boiling point of 100 0., which boiling points are close to thoseof benzene, 80.1 C'., and of n-heptane, 984 C., respectively. Thus, therecovery of such fiuorocarbons from benzene and n-heptane in separatingsaid hydrocarbons from a mixture containing the same, is difficult.

A more desirable fluorocarbon solvent for resolviing a mixturedffbenzene-and n-"heptane, is perflirorornet'hyldecal boi'ling point 'l64i0:

l: Th'process of resolving a hydrocarbon mixtur'e'containihg'aroinatic'and non-aromatic'hydrocarbon'sfinto fractions of"different degrees of aroniat'icity; whiclicomprises: contacting themixture with asolventlA) "comprising a fluorocarbon'represented"by the"generalformula where n rsnresaats e were? carhqn heme and an inte er 292- abqctair; #9 about twenty and i1represents the number oi fluorineairings ns-Ban in e ree! abqut i h to bo forty, and with a second o1vent(Blhaving the eateries-lice s s fal en-ins. i

miscibility with. the hydrocarbon (1) Incomplete mixture; v(2)Incbmplete miscibility with the fluorocarbon A3,. 7 (M .b (3') Formsthree .phases with the hydrocarbon mixture andthe'fiuo'rocarbon" (A);"and i Has preier ntial aff it for aromatic hydrocarbons;

effecting phase separation of the phases thus remea -a flaorocarteirrmextract phase','aso1-' vent (B) extract phase, and sh'ydrecarbbp phase.ix'ffi bi l fl .7 we r ar m ia i i b 'j' t em: degresiof aromat ty,which comprise e e e insff'tlie .INQ 'HQQP' WPM Ps u rc carbonrpresentedby' the generahformula' where n represents he umber of rb atms a dir n i i1 ""t f0'ur' watch my n rc e t thi m fi ne l, Qritfeg froma out eight to about N a {99 i B a n he followingcharacteri' ieaturesf 1A Incomp te m scib l t twitht e h r ca 2 lncornpletc mis ilit ,With thefluorocari u m .i 5,3) ,Eorms t re s s my h t e rdro a n 41 a a: ar masyqiil s i 9 19 5112 than ch s sae a? attr c cha ta a hrqr sa hoe hasedehyde, cinnamyl alcohol, 2,4-dinitrochlorobenzene, diethylene glycol,dipropylene glycol, diethylene glycol monomethyl ether,pe'-irninodipropicnitrile, ,Bp'oxydipropionitrile,csthiodipropionitrile, ethylene diamine, ethylene diformate, ethylsulfate, ethyl tartrate, furfural, formanilide, furfuryl alcohol,,B-hydroxyethylacetate, p-hydroxypropionitrile, lactic acid, maleicanhydride, methanol, fl-methoxyethanol, methyl furoate, methylphthalate, methyl sulfate, monoacetin, onitroanisole, nitrobenzene,nitromethane, phenetidines, phenol, phenyl phthalate,phenylethyanolamine, piperonal, liquid sulfur dioxide,tetrahydrofurfuryl alcohol, triethylene glycol and succinonitrile.

5. The process of claim 1 wherein the solvent (B) is triethylene glycol.

6. The process of claim 1 wherein the solvent (B) is acetonitrile.

7. The process of claim 1 wherein the hydrocarbon mixture is one boilingbelow about 150 C.

8. The process of claim 1 wherein the hydrocarbon mixture is onecontaining benzene and non-aromatic hydrocarbons boiling between about70 C. and 90 C.

9. The process of claim 1 wherein the hydrocarbon mixture comprisesaromatic and aliphatic hydrocarbons.

10. The process of claim 1 wherein the hydrocarbon mixture comprisesaromatic and naphthenic hydrocarbons.

11. The continuous process for separating a hydrocarbon mixturecontaining aromatic and nonaromatic hydrocarbons into fractions ofdifierent degrees of aromaticity which comprises: contacting the mixturewith a solvent (A) compris ing a fluorocarbon represented by the generalformula wherein' .1: represents the number of carbon atoms and is aninteger from about four to about twenty and y represents the number offluorine atoms and is an integer from about eight to about forty, andwith a second solvent (B) having the following characterizing features:

(1) Incomplete miscibility with the hydrocarbon mixture;

(2) Incomplete miscibility with the fluorocarbon (A);

(3) Forms three phases with the hydrocarbon mixture and fluorocarbon (A)and (4) Has a preferential aflinity for aromatic hydrocarbons;

efiecting phase separation of the phases thus formed, a fluorocarbon (A)extract phase, a solvent (B) extract phase, and a hydrocarbon phase;removing fluorocarbon (A) from the fluorocarbon (A) extract phase,thereby obtaining a hydrocarbon fraction of less aromaticity than theoriginal hydrocarbon mixture, and removing from the system said lessaromatic hydrocarbon fraction; removing solvent (B) from the solvent (B)extract phase, thereby obtaining a hydrocarbon fraction of greateraromaticity than the original hydrocarbon mixture, and removing 12 fromthe system saidmore aromatic hydrocar bon fraction; and recycling tosaid contacting operation the said fluorocarbon (A) and said solvent (B)removed from their respective extract phases.

12. The process of resolving a hydrocarbon mixture containing aromaticand non-aromatic hydrocarbons into fractions of different degrees ofaromaticity, which'comprisesz contacting the mixture with a solvent (A)selected from the group consisting of:

(a) A fluorocarbon represented by the general formula CmFy wherein 1:represents the number of carbon atom and is an integer from about fourto about twenty and y represents the number of fluorine atoms and is aninteger from about eight to about forty,

(b) A highly fiuorinated hydrocarbon having at least about four carbonatoms per molecule and in which at least about eighty per cent of thehydrogen of the parent hydrocarbon has been replaced by fluorine, V

and,

(c) A highly fluorinated hydrocarbon having at least about four carbonatoms per molecule and in which at least about eighty per cent of thehydrogen of the parent hydrocarbon has been replaced by fluorine and inwhich additional hydrogenof the parent hydrocarbon has been replaced byhalogen other than fluorine,

and with a second solvent (B) having the following characterizingfeatures:

(1) Incomplete miscibility with the hydrocarbon mixture;

(2) Incomplete miscibility with the fluorocarbon (3) Forms three phaseswith the hydrocarbon mixture and the fluorocarbon (A) and (4) Has apreferential affinity for aromatic hydrocarbons;

effecting phase separation of the phases thus formed, a fluorocarbon (A)extract phase, a solvent (B) extract phase, and a hydrocarbon phase.

ALFRED W. FRANCIS. GEORGE C. JOHNSON.

References Cited. i the file of this patent UNITED STATES PATENTS NumberName Date 1,912,349 iuttle May 30, 1933 2,295,612 Soday Sept. 15, 19422,463,479 Denton et al Mar. 1, 1949 2,582,197 Egan Jan. 8, 1952 OTHERREFERENCES I Kalichevsky, Modern Methods of Refining Lubricating Oils,pages -157 (1932). Reinhold Pub. Co.

1. THE PROCESS OF RESOLVING A HYDROCARBON MIXTURE CONTAINING AROMATICAND NON-ARMATIC HYDROCARBONS INTO FRACTIONS OF DIFFERENT DEGREES OFAROMATICITY, WHICH COMPRISES: CONTACTING THE MIXTURE WITH A SOLVENT (A)COMPRISING A FLUOROCARBON REPRESENTED BY THE GENERAL FORMULA